In the combustion of a fuel, such as coal, oil, natural gas, peat, waste, etc., in a combustion plant, such as those associated with boiler systems for providing steam to a power plant, a hot process gas (or flue gas) is generated. Such a flue gas will often contain, among other things, carbon dioxide (CO2). The negative environmental effects of releasing CO2 to the atmosphere have been widely recognized, and have resulted in the development of processes adapted for removing CO2 from the hot process gas generated in the combustion of the above mentioned fuels. Systems and methods for removing CO2 from a gas stream include CO2 capture systems in which a flue gas is contacted with an aqueous absorbent solution such as, for example, a chilled ammonia based ionic solution.
Chemical adsorbtion with amines is also one such CO2 capture technology being explored. Capturing CO2 gas from a flue gas stream by subjecting the flue gas stream to an adsorbent that is coated onto a solid material or substrate is sometimes referred to an adsorbent coated substrate (ACS). There are two types of these coated substrates—one in which amines are attached via adsorbtion and another in which amines are covalently attached to the substrate. Amines can be used as the adsorbent because they can be coated on the solid material and are useful for CO2 capture because they can increase the capacity of the CO2. However, the flue gases also contain strong acid gases such as sulfur dioxide (SO2) and sulfur trioxide (SO3) which react with the amines and reduce the ability of the amine to react with and adsorb CO2.